Wetting front advance and freezing of meltwater within a snow cover: 2. A simulation model

A simulation model is developed which incorporates the effect of flow fingers at the leading edge of the wetting front, ice layer growth within and at the base of the snow cover, and meltwater infiltration into the underlying frozen soils. The model results demonstrated that ice layers grow rapidly over a 24‐ to 36‐hour period due to the conduction of heat into the snow and underlying soil. Sufficient water is frozen as ice layers to slow the finger wetting front and to account for the rapid snow and soil warming. Wetting front advance and ice layer growth were found to be sensitive to snow temperature, thermal conductivity, volume of flow in the fingers, and irreducible water saturation. Simulation of a warm snow cover showed that with reduced ice layer growth the flow fingers were able to transmit rapidly water to the snow cover base before the entire snow cover was wet. In the arctic situation the soil was sufficiently cold to ensure basal ice growth throughout the melt period. Basal ice growth was found to be sensitive to soil infiltration, length of the growing period, and the snowmelt rate. As a result of the negative soil heat flux, all meltwater is not available for runoff until both the liquid and thermal requirements of the snow and soil have been satisfied.